New Zealand bans sale of assault, semi-automatic rifles

New Zealand has banned the sale of assault rifles and semi-automatic weapons after the country's worst-ever attack that killed 50 people in two mosques. 

"Be assured this is just the beginning of the work we'll be doing," Prime Minister Jacinda Ardern told a news conference on Thursday.

"It's in the national interest and it's about safety ... to prevent an act of terror from ever happening again in our country," she said of the ban.

Ardern said she expects the new law to be in place by April 11 and buy-back schemes will be established for banned weapons. 

"Now, six days after this attack, we are announcing a ban on all military-style semi-automatics (MSSA) and assault rifles in New Zealand," Ardern said.

She said the man arrested in the attacks on two Christchurch mosques had purchased his weapons legally and enhanced their capacity by using 30-round magazines "done easily through a simple online purchase".

"Related parts used to convert these guns into MSSAs are also being banned, along with all high-capacity magazines," she said. 

"In short, every semi-automatic weapon used in the terrorist attack on Friday will be banned in this country."

Ardern said the interim measures announced on Thursday will stop a rush of purchases before legislation on the measures takes effect next month.

She added there would be some limited exemptions for New Zealand's farmers, many of whom require firearms for pest control and management of their livestock.

Previous governments failed to implement recommendations made by Justice Thomas Thorp in his government-backed 1997 review of firearms control in New Zealand.

Thorp's review culminated in a call for all firearms to be individually registered to their owners, tighter vetting procedures for those seeking to buy weapons and a ban on military style semi-automatics.

"This isn't knee jerk by any stretch, these measures have been well considered and overdue," Gilbert said.

"Nobody is saying that New Zealanders can't have a firearm ... New Zealand is a country that requires firearms, but no one needs a military-style semi-automatic weapon," he added, citing the example of farmers.

"We allow people to drive cars in New Zealand we don't allow people to drive tanks, that's the equivalence … The time for these measures isn't now, it's actually long passed."

Following Ardern's announcement, Police Commissioner Bush said there would be an "amnesty" to allow people to hand in now illegal firearms to police.

"For many people, you will now be in unlawful possession of your firearm," Bush said in a statement.

New Zealand's foremost hunting body, Fish and Game NZ, said on Wednesday it would support a ban and buy-back of military-style semi-automatic weapons and restrictions on high-capacity magazines.